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.TH MBSRTOWCS 3C "December 28, 2020"
.SH NAME
mbsnrtowcs, mbsnrtowcs_l, mbsrtowcs, mbsrtowcs_l \- convert a character string
to a wide-character string (restartable)
.SH SYNOPSIS
.nf
#include <wchar.h>

\fBsize_t\fR \fBmbsnrtowcs\fR(\fBwchar_t *restrict\fR \fIdst\fR, \fBconst char **restrict\fR \fIsrc\fR,
     \fBsize_t\fR \fInms\fR, \fBsize_t\fR \fIlen\fR, \fBmbstate_t *restrict\fR \fIps\fR);
.fi
.LP
.nf
\fBsize_t\fR \fBmbsrtowcs\fR(\fBwchar_t *restrict\fR \fIdst\fR, \fBconst char **restrict\fR \fIsrc\fR,
     \fBsize_t\fR \fIlen\fR, \fBmbstate_t *restrict\fR \fIps\fR);
.fi
.LP
.nf
#include <wchar.h>
#include <xlocale.h>

\fBsize_t\fR \fBmbsnrtowcs_l\fR(\fBwchar_t *restrict\fR \fIdst\fR, \fBconst char **restrict\fR \fIsrc\fR,
     \fBsize_t\fR \fInms\fR, \fBsize_t\fR \fIlen\fR, \fBmbstate_t *restrict\fR \fIps\fR, \fBlocale_t\fR \fIloc\fR);
.fi
.LP
.nf
\fBsize_t\fR \fBmbsrtowcs_l\fR(\fBwchar_t *restrict\fR \fIdst\fR, \fBconst char **restrict\fR \fIsrc\fR,
     \fBsize_t\fR \fIlen\fR, \fBmbstate_t *restrict\fR \fIps\fR, \fBlocale_t\fR \fIloc\fR);
.fi
.SH DESCRIPTION
These function converts a sequence of characters, beginning in
the conversion state described by the object pointed to by \fIps\fR, from the
array indirectly pointed to by \fIsrc\fR into a sequence of corresponding
wide-characters. If \fIdst\fR is not a null pointer, the converted characters
are stored into the array pointed to by \fIdst\fR. Conversion continues up to
and including a terminating null character, which is also stored.  Conversion
stops early in either of the following cases:
.RS +4
.TP
.ie t \(bu
.el o
When a sequence of bytes is encountered that does not form a valid character.
.RE
.RS +4
.TP
.ie t \(bu
.el o
When \fIlen\fR codes have been stored into the array pointed to by \fIdst\fR
(and  \fIdst\fR is not a null pointer).
.RE
.LP
Each conversion takes place as if by a call to the \fBmbrtowc()\fR function.
.LP
If \fIdst\fR is not a null pointer, the pointer object pointed to by \fIsrc\fR
is assigned either a null pointer (if conversion stopped due to reaching a
terminating null character) or the address just past the last character
converted (if any).  If conversion stopped due to reaching a terminating null
character, and if \fIdst\fR is not a null pointer, the resulting state
described is the initial conversion state.
.LP
If \fIps\fR is a null pointer, these functions uses their own
internal \fBmbstate_t\fR object, which is initialized at program startup to the
initial conversion state.  Otherwise, the \fBmbstate_t\fR object pointed to by
\fIps\fR is used to completely describe the current conversion state of the
associated character sequence. The system will behave as if no function defined
in the Reference Manual calls any of these functions.
.LP
The function \fBmbsnrtowcs()\fR behaves identically to \fBmbsrtowcs()\fR,
except the conversion stops after reading \fInms\fR bytes from the
buffer pointed to by \fIsrc\fR.
.LP
The behavior of \fBmbnrtowcs()\fR and \fBmbsrtowcs()\fR functions are
affected by the \fBLC_CTYPE\fR category of the
current locale.  See \fBenviron\fR(7). The functions \fBmbsrtowcs_l()\fR and
\fBmbsnrtowcs_l()\fR behave identically to \fBmbsrtowcs()\fR and
\fBmbsnrtowcs()\fR, except that instead of using the current locale, they use
the locale specified by \fIloc\fR.
.SH RETURN VALUES
If the input conversion encounters a sequence of bytes that do not form a valid
character, an encoding error occurs.  In this case, these
functions store the value of the macro \fBEILSEQ\fR in \fBerrno\fR and return
\fB(size_t)\(mi1\fR; the conversion state is undefined.  Otherwise, they return
the number of characters successfully converted, not including the terminating
null (if any).
.SH ERRORS
These functions may fail if:
.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The \fIps\fR argument points to an object that contains an invalid conversion
state.
.RE

.sp
.ne 2
.na
\fB\fBEILSEQ\fR\fR
.ad
.RS 10n
Invalid character sequence is detected.
.RE
.SH ATTRIBUTES
See \fBattributes\fR(7) for descriptions of the following attributes:
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	See below.
_
MT-Level	See below.
.TE

.LP
The
.B mbsnrtowcs()
and
.B mbsrtowcs()
functions are Standard.  The
.B mbsnrtowcs_l()
and
.B mbsrtowcs_l()
functions are Uncommitted.
.LP
If \fIps\fR is not a null pointer, these functions use the \fBmbstate_t\fR
object pointed to by \fIps\fR and can be used safely in
multithreaded applications, otherwise they use an
internal \fBmbstate_t\fR object and are Unsafe in multithreaded
applications.
.SH SEE ALSO
\fBmbrtowc\fR(3C), \fBmbsinit\fR(3C), \fBnewlocale\fR(3C),
\fBsetlocale\fR(3C), \fBuselocale()\fR, \fBattributes\fR(7),
.BR environ (7),
.BR standards (7)
